CN112855111A - Underground gasification system and method for electric heating coal bed - Google Patents
Underground gasification system and method for electric heating coal bed Download PDFInfo
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- CN112855111A CN112855111A CN201911190913.3A CN201911190913A CN112855111A CN 112855111 A CN112855111 A CN 112855111A CN 201911190913 A CN201911190913 A CN 201911190913A CN 112855111 A CN112855111 A CN 112855111A
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/295—Gasification of minerals, e.g. for producing mixtures of combustible gases
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
- E21B43/168—Injecting a gaseous medium
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/20—Displacing by water
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
- E21B43/2401—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection by means of electricity
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/267—Methods for stimulating production by forming crevices or fractures reinforcing fractures by propping
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/30—Specific pattern of wells, e.g. optimizing the spacing of wells
- E21B43/305—Specific pattern of wells, e.g. optimizing the spacing of wells comprising at least one inclined or horizontal well
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
- E21B7/046—Directional drilling horizontal drilling
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/10—Geothermal energy
Abstract
The invention provides an underground gasification system and method of an electric heating coal bed, and the method comprises the following steps: the data processing device screens target horizons meeting preset conditions; the drilling device drills a plurality of rows of horizontal wells at the target layer according to the direction perpendicular to the maximum main stress; according to the depth of a target horizon, sequentially using horizontal wells positioned between the deepest position and the shallowest position as a heating well and a production well; the fracturing device carries out staged fracturing operation on multiple rows of horizontal wells, and after fracturing is finished, a propping agent is injected to keep fractures in an open state; the electric heating device and the production device respectively carry out different injection operations and heating operations on the multiple rows of heating wells and carry out different production operations on the multiple rows of production wells. The scheme can effectively reduce the complexity of operation, improve the production efficiency of the coal bed, and improve the utilization effect and gasification effect of the deep coal bed.
Description
Technical Field
The invention relates to the technical field of coal seam development, in particular to an underground gasification system and method for an electric heating coal seam.
Background
The Underground Coal Gasification technology (UCG) is also called as in-situ Coal Gasification, and the process is to convert the Coal bed existing Underground from physical Coal mining to chemical Coal mining, and the essential thing is to convert the useful substances (volatile components, fixed carbon and the like) in the Coal into combustible gas through physical and chemical conversion modes such as pyrolysis, combustion, Gasification and the like. UCG comprises well type and non-well type coal underground gasification processes, integrates well building, coal mining and gasification into a whole, and has the advantages of low gas production cost, high safety and good environmental benefit. The cost of the gas produced by the UCG is only 25-50% of that of the ground gasification furnace, and the UCG can be used as the raw material gas for gas power generation, boiler fuel and synthetic chemical products, so that the cost of power generation or synthetic chemical products is obviously reduced. UCG still has apparent environmental benefit, reduces the emission of coal fired pollution, gangue and lime-ash greatly, effectively solves the atmosphere haze problem that present coal-fired arouses, and combines together with carbon entrapment and sequestration technique, can effectively reduce greenhouse gas and discharge. UCG is a coal development method, is an innovation of the traditional coal mining mode, and is known as a second generation coal mining method; from the benefit, the method is a new technology for developing clean energy by low carbon of high carbon resources. The technology has wide application prospect in the aspects of mining and utilization of residual coal such as low-quality (high-sulfur and high-ash), steep inclined, thin coal bed, deep coal bed, coal pressing under the third coal bed, conventional technology economy, non-mining and the like.
At present, the coal underground gasification does not realize industrialized production, and one important reason is that the scale of the coal underground gasification is small and the gas production is unstable. On one hand, under the influence of external hydrological and geological environment, the conditions (coal thickness, coal quality and the like) and occurrence conditions (geology, hydrology, structure and the like) of a gasified coal bed are complex and variable, the difficulty is increased for the underground gasification process of the coal, and the factors needing manual regulation and control are more; secondly, the control means of the underground coal gasification process is limited, and is influenced by factors such as high temperature, gas, coal body thermal fracture, surrounding rock stress, overlying strata collapse, fissure zone development and the like of an underground gasification space, so that effective monitoring and control means are difficult to be adopted like an underground coal gas producer, and the difficulty of artificial regulation and control is increased.
In the prior art, scholars at home and abroad propose different types of underground coal gasification furnace structures and gasification production methods aiming at different coal seam occurrence conditions. In the aspect of the construction of the gasification furnace type, from the distribution positions of the gas injection channel, the gasification channel and the exhaust channel, the underground gasification furnace can be divided into a plurality of furnace types, namely a blind hole furnace, a one-line furnace, a V-shaped furnace, a U-shaped furnace, an E-shaped furnace and the like, and then a porous furnace and a long fireplace capable of converting the gas injection and exhaust operations are invented. The research direction of overseas underground gasification is mainly a well-free coal underground gasification process, a coal underground gasification furnace is constructed by drilling on the ground, and the well-free gasification process which is relatively mature comprises a linear Injection Point retreat process (CRIP) and a parallel directional drilling CRIP process. The existing well type coal underground gasification process adopts two adjacent vertical well bores as an injection well and a gas production well of a gasification agent respectively, then adopts various communication methods (such as fire communication, electric power communication, reverse combustion, air fracturing and the like) to enable the bottoms of the two vertical well bores to be communicated in a coal seam to form a gasification channel, and then the gasification agent is blown in from the gas injection well to produce gas from the gas production well. The furnace building process of the gasification furnace has the defects of low penetration speed, poor penetration directionality, difficult penetration or impossible penetration when the vertical well spacing is large; the vertical drilling distance is small, the number of vertical drilling is large during continuous production, and the investment is large; a gas injection device is not arranged in the gasification furnace, and the gasification agent is diffused and combusted in the whole gasification furnace, so that the combustion range and the boundary can not be effectively controlled, and the gas production quality is low; the enlarged combustion range causes large area collapse of the overlying strata, and the stability control effect of the surrounding rocks is poor. According to the existing well-free CRIP process, a drawtube type mobile gas injection point device is adopted in the aspect of gas injection control, a gas injection point is pulled backwards periodically, the gas injection point is pulled backwards for a certain distance every time, a large-scale gas injection elbow spiral pulling device needs to be built on the ground, the equipment investment is high, the process operation is complex, the gas injection elbow is difficult to seal at the ground end, and when the coal seam buries deeply, the operation reliability of the mobile gas injection device is reduced under the influence of geological stress and drilling deformation.
Therefore, in order to solve the problems of the existing underground coal gasification furnace production system, the underground coal gasification furnace production system and the process which are adaptive to geological environment and have a controllable function need to be developed, and technical support is provided for further realizing the industrialization of underground coal gasification.
Disclosure of Invention
The embodiment of the invention provides an electric heating coal seam underground gasification system and method, and solves the technical problems that in the prior art, the production system of an underground coal gasification furnace is high in operation complexity, low in coal seam production efficiency and the like.
The embodiment of the invention provides an underground gasification system of an electric heating coal bed, which comprises:
the device comprises a data processing device, a drilling device, a fracturing device, an electric heating device, a production device and a monitoring device;
the data processing apparatus is configured to: screening a target layer position meeting preset conditions, determining the distribution condition of the horizontal well according to the depth and the thickness of the target layer position, and determining the fracturing operation condition of the horizontal well and the injection heating and production operation condition of the horizontal well according to the distribution condition of the horizontal well;
the drilling apparatus is for: drilling a plurality of rows of horizontal wells at a target layer according to the direction perpendicular to the maximum main stress direction based on the distribution condition of the horizontal wells;
according to the depth of a target horizon, horizontal wells positioned between the deepest position and the shallowest position are sequentially used as a heating well and a production well;
the fracturing device is used for: performing staged fracturing operation on multiple rows of horizontal wells according to the fracturing operation condition of the horizontal wells, and injecting a propping agent to keep fractures in an open state after fracturing is completed;
the electric heating device and the production device are respectively used for: according to the injection heating and production operation conditions of the horizontal well, temperature data, pressure data and gas production data in the water injection operation and heating operation processes monitored by a monitoring device, different injection operations and heating operations are carried out on the multiple rows of heating wells, and different production operations are carried out on the multiple rows of production wells.
The embodiment of the invention also provides an underground gasification method of the electric heating coal bed, which comprises the following steps:
the data processing device screens a target layer position meeting preset conditions, determines the distribution condition of the horizontal well according to the depth and the thickness of the target layer position, and determines the fracturing operation condition of the horizontal well and the injection heating and production operation condition of the horizontal well according to the distribution condition of the horizontal well;
the drilling device drills a plurality of rows of horizontal wells at a target layer according to the direction perpendicular to the maximum main stress direction based on the distribution condition of the horizontal wells; according to the depth of a target horizon, horizontal wells positioned between the deepest position and the shallowest position are sequentially used as a heating well and a production well;
the fracturing device performs staged fracturing operation on multiple rows of horizontal wells according to the fracturing operation condition of the horizontal wells, and injects a propping agent to keep fractures in an open state after fracturing is completed;
the electric heating device and the production device respectively perform different injection operations and heating operations on the multiple rows of heating wells and perform different production operations on the multiple rows of production wells according to the injection heating and production operation conditions of the horizontal well, and the temperature data, the pressure data and the gas production data in the water injection operation and heating operation processes monitored by the monitoring device.
The embodiment of the present invention further provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the method when executing the computer program.
The embodiment of the invention also provides a computer readable storage medium, and the computer readable storage medium stores a computer program for executing the method.
In the embodiment of the invention, a target layer meeting preset conditions is screened through a data processing device, the distribution condition of a horizontal well is determined according to the depth and the thickness of the target layer, the fracturing operation condition of the horizontal well and the injection heating and production operation condition of the horizontal well are determined according to the distribution condition of the horizontal well, a plurality of rows of horizontal wells are drilled in the target layer according to the direction vertical to the maximum principal stress direction on the basis of the distribution condition of the horizontal well through a drilling device, and the horizontal wells between the deepest position and the shallowest position are sequentially used as a heating well and a production well according to the depth of the target layer; the method comprises the steps of performing staged fracturing operation on multiple rows of horizontal wells through a fracturing device according to fracturing operation conditions of the horizontal wells, injecting a propping agent to keep fractures in an open state after fracturing is completed, performing different injection operations and heating operations on the multiple rows of heating wells through an electric heating device and a production device according to water injection heating production operation conditions of the horizontal wells and temperature data, pressure data and gas production data in the water injection operation and heating operation processes monitored by a monitoring device, and performing different production operations on the multiple rows of production wells.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a well pattern deployment for an efficient method of electrically heating a subterranean gasification coal seam according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a horizontal well bore structure for an efficient method of heating a subterranean gasification coal seam according to an embodiment of the present invention;
FIG. 3 is a flow chart of a method for underground gasification of an electrically heated coal seam according to an embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In an embodiment of the present invention, an electrically heated coal seam underground gasification system is provided, including: the device comprises a data processing device, a drilling device, a fracturing device, an electric heating device, a production device and a monitoring device;
the data processing apparatus is configured to: screening a target layer position meeting preset conditions, determining the distribution condition of the horizontal well according to the depth and the thickness of the target layer position, and determining the fracturing operation condition of the horizontal well and the injection heating and production operation condition of the horizontal well according to the distribution condition of the horizontal well;
the drilling apparatus is for: drilling a plurality of rows of horizontal wells at a target layer according to the direction perpendicular to the maximum main stress direction based on the distribution condition of the horizontal wells;
according to the depth of a target horizon, horizontal wells positioned between the deepest position and the shallowest position are sequentially used as a heating well and a production well;
the fracturing device is used for: performing staged fracturing operation on multiple rows of horizontal wells according to the fracturing operation condition of the horizontal wells, and injecting a propping agent to keep fractures in an open state after fracturing is completed;
the electric heating device and the production device are respectively used for: according to the water injection heating production operation condition of the horizontal well, the temperature data, the pressure data and the gas production data in the water injection operation and the heating operation process monitored by the monitoring device, different injection operations and heating operations are carried out on the multiple rows of heating wells, and different production operations are carried out on the multiple rows of production wells.
In an embodiment of the present invention, the data processing apparatus is specifically configured to:
acquiring the depth, the thickness and the component conditions of a coal seam to be treated;
screening a target layer meeting preset conditions according to the depth and the thickness of a coal seam to be treated and the conditions of components contained in the coal seam;
the preset conditions include: the depth of the target layer is smaller than a preset depth threshold, the thickness of the target layer is larger than a thickness threshold, and the component condition of the target layer is larger than a preset component threshold;
the preset depth threshold value is 2000m, and the thickness threshold value is 10 m.
In addition, the preset conditions further comprise: the coal seam has a good cover layer, and no fault is formed in the area.
In an embodiment of the present invention, the data processing apparatus is specifically configured to:
and determining the row number and row spacing of the horizontal wells drilled in the target horizon, the well spacing between two horizontal wells in each row, the length of each horizontal well, the distance between the deepest horizontal well and the bottom of the target horizon and the distance between the shallowest horizontal well and the top of the target horizon according to the depth and the thickness of the target horizon.
According to the direction perpendicular to the maximum main stress, a plurality of horizontal wells are drilled in parallel at the position 3-5m above the bottom of a target layer, the well distance is 10-20 m, the length of each horizontal well is 200-1500 m, a plurality of horizontal wells are deployed in parallel at the position 10-15 m above a row of horizontal wells at the lower part, and the well distance is 10-20 m. And according to the thickness of the coal seam, repeatedly and parallelly deploying a plurality of horizontal wells in the vertical direction, deploying horizontal well rows 3-5m away from the top of the target horizon, controlling the thickness of the whole oil reservoir completely, wherein the length of each horizontal well is 200-1500 m, and the distance between every two adjacent horizontal wells is 100-200 m.
For example, when it is determined that three horizontal drainage wells are drilled in the target horizon, the bottom row is a heater well, the middle row is a production well first, and then is a heater well when it cannot produce, and the top row is a production well;
when it is determined that four horizontal rows of wells are drilled in the target horizon, the bottom row is a heater well, the penultimate row is first a producer well and then a heater well when it cannot produce, and the top row is a producer well.
In the embodiment of the invention, the horizontal well is in a multi-branch well form;
the data processing apparatus is specifically configured to:
the spacing of the branches, the length of each branch well, and the well spacing per branch well are determined.
All horizontal intervals described above are completed with slotted screens.
In an embodiment of the present invention, the data processing apparatus is specifically configured to:
determining the number of fracturing sections and the section distance of each section according to the length of each horizontal well;
the fracturing device is specifically used for:
and performing staged fracturing operation on each horizontal well according to the number of fracturing sections and the section distance of each section, and injecting a propping agent to keep the fracture in an open state after fracturing is completed.
Specifically, staged fracturing operation is carried out on all heating horizontal wells in the coal seam, a stage is set to be 80-100 m along the horizontal well section, 10-15 stages are fractured on each horizontal well, and the coal seam is segmented into criss-cross blocky structures.
In the embodiment of the invention, the electric heating device is an electric heater, a packer and an injection pipeline;
an electric heating device and a monitoring device are placed in the heating well, and lifting equipment and the monitoring device are placed in the production well;
the monitoring device comprises temperature detection equipment, pressure detection equipment, gas concentration detection equipment and gas yield detection equipment.
In the embodiment of the invention, a high-power electric heater, a packer, a monitoring device and the like are arranged in a row of horizontal wells close to the bottom of an oil reservoir and used as heating wells. And (4) descending lifting equipment into the upper row of adjacent horizontal wells to serve as production wells. And the rest of the well rows are analogized in turn.
The heating well at the deepest and the production wells in the row above are operated as follows:
the heater heats the heating well at the deepest position according to a first preset heating temperature (such as 500-800 ℃) and a first preset heating power (such as 1-2 MW);
injecting water into the heating well at the deepest position by an injection pipeline according to first preset water injection data (such as the water injection speed is 1.5-3 t/h, and the water injection amount is 20t), wherein the first preset water injection data comprises the water injection speed and the water injection amount;
when pressure detection equipment in the heating well detects that the formation pressure reaches a first preset formation pressure (such as 12MPa), stopping injecting water;
supplementing and quantitatively injecting water through an injection pipeline according to the pressure detected by the pressure detection equipment in real time, and keeping the pressure coefficient within a first preset pressure coefficient range (such as 0.8-1.2);
in a shaft above the packer, the pressure is maintained by supplementing a water column through an injection pipeline, so that the failure of the packer is prevented;
observing the rise condition of casing pressure in a casing of the production well, and when the pressure detection equipment and the gas concentration detection equipment in the production well in the previous row detect that the casing pressure in the production well reaches a first preset casing pressure (for example, more than 0.5 MPa) and the gas concentration reaches a first preset gas concentration (for example, the methane concentration is more than 95%), starting the lifting equipment in the production well to work; the temperature of the heater is kept between 500 ℃ and 800 ℃ (other values are also possible).
Observing the temperature change condition near the production well, when the temperature detection equipment in the previous row of production wells detects that the temperature of the production well rises to a first preset temperature (for example, more than 200 ℃), reducing the heating temperature of a heater in a heating well to a second preset heating temperature (for example, 400-500 ℃), and controlling the bottom temperature of the production well to be not more than 200 ℃ (or other values);
when the gas production detecting device in the production well in the previous row detects that the daily gas production of the production well is lower than a first preset daily gas production (for example, 500 m)3During the time of the production, stopping the lifting equipment in the production well;
the following operations are repeated for horizontal wells between the deepest and shallowest, which in turn are heating wells and production wells:
heating a row of horizontal wells serving as heating wells by heaters according to a second preset heating temperature (such as 500-800 ℃) and a second preset heating power (such as 2MW), stopping heating when heating for a first preset number of days, injecting gas into the heating wells according to first preset gas injection data through injection pipelines, and starting lifting equipment in the row of horizontal wells above the row of heating wells when pressure detection equipment and gas concentration detection equipment detect that the casing pressure in the heating wells reaches a second preset casing pressure and the gas concentration reaches a second preset gas concentration (namely H2 concentration); the second preset heating temperature is greater than the first preset heating temperature, and the second preset heating power is greater than the first preset heating power;
and when the temperature detection device and the gas concentration detection device in the horizontal well in the row above the heating well in the row detect that the temperature in the horizontal well reaches a second preset temperature (such as 200 ℃), and the gas concentration reaches a third preset gas concentration (namely the O2 concentration exceeds 5%), the lifting device in the horizontal well stops working.
The following is a description of specific examples.
Example 1
The depth of a target coal seam is 1120m, the thickness of the target coal seam is 20m, a mudstone layer with the thickness of 60-100 m is arranged above the coal seam, the coal quality belongs to lignite, the ash content is 13%, the volatile matter is 57%, the water content is 10%, and the fixed carbon is 20%. Measuring the methane adsorption capacity at 37m3/m3。
Screening a target horizon, wherein the depth is less than 2000m, the thickness is more than 10m, the coal seam has a better cover layer (the cover layer is a protective layer which is positioned above the reservoir layer and can seal the reservoir layer to prevent oil gas in the reservoir layer from escaping upwards), and the methane adsorption capacity>20m3/m3Content of volatile matter>There were no faults in the 20% region.
And 2, according to the direction perpendicular to the maximum main stress, a plurality of horizontal wells are drilled in parallel at the position 3m above the target bottom, the well distance is 10m, the length of each horizontal well is 400m, a plurality of horizontal wells are deployed in parallel at the position 10m above a row of horizontal wells at the lower part, and the well distance is also 10 m. According to the thickness of the coal seam, only two rows of horizontal heating wells are deployed, a production horizontal well row is deployed at a position 3m away from the top of the coal seam, and the length of the horizontal well is 400 m. As shown in fig. 1.
In this embodiment, a branching operation is performed on horizontal wells, as shown in fig. 2, the horizontal well has a branch distance of 90m, a branch length of 70m, and an adjacent horizontal well distance of 100 m.
The horizontal well branches were completed with slotted screens.
And 3, performing staged fracturing operation on the horizontal heating well in the coal bed. And a subsection is set along the horizontal well section 80m, 5 sections are fractured by each horizontal well, and the coal bed is divided into criss-cross blocky structures. And injecting quartz sand proppant with the particle size of 1mm after fracturing is completed to keep the crack in an open state.
And 4, setting a 1MW high-power electric heater, a packer, a pressure monitoring device and the like as a heating well in a row of horizontal wells close to the bottom of the oil reservoir. And (4) descending lifting equipment into the upper row of adjacent horizontal wells to serve as production wells. And a row of horizontal wells at the top are used as production wells.
And 5, lowering an injection pipeline in the heating well.
And 6, turning on a heater in the heating well, setting the heating temperature to be 500-800 ℃, and heating the power to be 1 MW. Injecting water to the vicinity of the heating well of the target zone through an injection pipeline, wherein the water injection speed is 1.5t/h, the formation pressure is increased to 12MPa after the water injection is carried out for 20t, and the water injection is stopped. Then, quantitatively injecting water is supplemented according to the pressure monitoring condition, and the pressure coefficient is kept between 0.8 and 1.2. And supplementing water columns in a shaft above the packer to maintain pressure, so that the packer is prevented from failing.
And 7, observing the casing pressure rise condition in the casing of the production well, increasing the casing pressure by 0.6MPa after 2 days in the production well, and simultaneously measuring the methane concentration by 97 percent, namely starting to open the production well for production. The heater temperature is maintained above 500 ℃.
And 8, observing the temperature change condition near the production well, and if the temperature near the production well rises to more than 200 ℃, reducing the heating temperature to 300-500 ℃, wherein the control target is that the bottom temperature of the production well does not exceed 200 ℃.
9, stable production of production well, 15 production well peaksThe value gas production reaches 40000 square/day. After 864 days of continuous production, the daily gas production of the average production well of a single well is less than 500m3And d, stopping production. The heater power was increased to 2MW in the middle row of heater wells and the heating temperature was set at 800 ℃. After 50 days of continuous heating, the heater was turned off, air injection was started, the air injection rate per well was maintained at 10000 square/day, and the production well casing temperature, pressure and H2 content were monitored.
And 10, opening the top production well to open the well to produce when the casing pressure exceeds 3MPa and the H2 content exceeds 10 percent. The sleeve pressure is kept above 3MPa in the production process.
11, after 389 days of continuous production, the temperature of the production well reaches 200 ℃ to produce O2The concentration exceeds 5 percent, and the whole operation process is stopped. Finally, the gasified coal amount of the single production well reaches 5.28 ten thousand tons, the peak value of the gas production amount reaches 40000 square/day, the accumulated gas production amount reaches 5723 ten thousand squares, the initial methane content reaches more than 70 percent, and after the temperature of the heater is increased, the contents of CO and H2 reach about 50 percent.
Based on the same inventive concept, the embodiment of the invention also provides an underground gasification method of the electrically heated coal bed, which is described in the following embodiments. The principle of solving the problems of the electric heating coal seam underground gasification method is similar to that of an electric heating coal seam underground gasification system, so the implementation of the electric heating coal seam underground gasification method can be referred to the implementation of the electric heating coal seam underground gasification system, and repeated parts are not repeated.
As shown in fig. 3, the method for underground gasification of the electrically heated coal seam comprises the following steps:
step 301: the data processing device screens a target layer position meeting preset conditions, determines the distribution condition of the horizontal well according to the depth and the thickness of the target layer position, and determines the fracturing operation condition of the horizontal well and the injection heating and production operation condition of the horizontal well according to the distribution condition of the horizontal well;
step 302: the drilling device drills a plurality of rows of horizontal wells at a target layer according to the direction perpendicular to the maximum main stress direction based on the distribution condition of the horizontal wells; according to the depth of a target horizon, horizontal wells positioned between the deepest position and the shallowest position are sequentially used as a heating well and a production well;
step 303: the fracturing device performs staged fracturing operation on multiple rows of horizontal wells according to the fracturing operation condition of the horizontal wells, and injects a propping agent to keep fractures in an open state after fracturing is completed;
step 304: the electric heating device and the production device respectively perform different injection operations and heating operations on the multiple rows of heating wells and perform different production operations on the multiple rows of production wells according to the injection heating and production operation conditions of the horizontal well, and the temperature data, the pressure data and the gas production data in the water injection operation and heating operation processes monitored by the monitoring device.
The embodiment of the present invention further provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the method when executing the computer program.
The embodiment of the invention also provides a computer readable storage medium, and the computer readable storage medium stores a computer program for executing the method.
In summary, the effective method for electrically heating an underground gasified coal seam provided by the invention is greatly improved compared with the existing coal seam gas development method: the production process of the invention is divided into two stages, wherein the first stage is a stage of exploiting coal bed first-stage pyrolysis gas by heating to about 200 ℃ with steam, and the second stage is an underground coal second-stage pyrolysis gasification stage by heating to 500-800 ℃ with an electric heater. 1) The initial steam heating has the advantages of uniformity and high efficiency, the whole coal bed after volume fracturing can be heated to more than 200 ℃, the volatile part in the coal bed can be extracted to the maximum extent to cause further cracking of shale oil, and the maximization of the output liquid oil is ensured. 2) The injected steam has longer contact time and higher temperature with the coal bed at higher temperature (500-800 ℃), has obvious modification effect on solid coking substances in the coal, and improves the conversion efficiency; because a large amount of first-stage pyrolysis gas is produced at the operation stage of 200 ℃, a large amount of volatile matters in the coal bed are volatilized, and the residual coke forms a porous medium and has certain permeability, so that conditions are provided for later stage water injection or gas injection; 3) air and oxygen are not injected in the process at the initial stage of operation, so that the safety of the operation process and the high quality of the produced gas are ensured. Air is injected to continue gasification at the later stage of the operation process, so that the full gasification of coke can be ensured, and the gasification efficiency is improved; 4) different from the ground coal gasification process, abundant metal elements in the coal bed can be used as catalysts, so that the conversion of immature substances in the coal bed is promoted, and the coal conversion efficiency is improved.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made to the embodiment of the present invention by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. An underground gasification system of an electric heating coal bed is characterized by comprising a data processing device, a drilling device, a fracturing device, an electric heating device, a production device and a monitoring device;
the data processing apparatus is configured to: screening a target layer position meeting preset conditions, determining the distribution condition of the horizontal well according to the depth and the thickness of the target layer position, and determining the fracturing operation condition of the horizontal well and the injection heating and production operation condition of the horizontal well according to the distribution condition of the horizontal well;
the drilling apparatus is for: drilling a plurality of rows of horizontal wells at a target layer according to the direction perpendicular to the maximum main stress direction based on the distribution condition of the horizontal wells;
according to the depth of a target horizon, horizontal wells positioned between the deepest position and the shallowest position are sequentially used as a heating well and a production well;
the fracturing device is used for: performing staged fracturing operation on multiple rows of horizontal wells according to the fracturing operation condition of the horizontal wells, and injecting a propping agent to keep fractures in an open state after fracturing is completed;
the electric heating device and the production device are respectively used for: according to the injection heating and production operation conditions of the horizontal well, temperature data, pressure data and gas production data in the air injection operation and heating operation processes monitored by a monitoring device, different injection operations and heating operations are carried out on the multiple rows of heating wells, and different production operations are carried out on the multiple rows of production wells.
2. The electrically heated coal seam underground gasification system of claim 1, wherein the data processing device is specifically configured to:
acquiring the depth, the thickness and the component conditions of a coal seam to be treated;
screening a target layer meeting preset conditions according to the depth and the thickness of a coal seam to be treated and the conditions of components contained in the coal seam;
the preset conditions include: the depth of the target layer is smaller than a preset depth threshold, the thickness of the target layer is larger than a thickness threshold, and the component condition of the target layer is larger than a preset component threshold;
the preset depth threshold value is 2000m, and the thickness threshold value is 10 m.
3. The electrically heated coal seam underground gasification system of claim 2, wherein the data processing device is specifically configured to:
and determining the row number and row spacing of the horizontal wells drilled in the target horizon, the well spacing between two horizontal wells in each row, the length of each horizontal well, the distance between the deepest horizontal well and the bottom of the target horizon and the distance between the shallowest horizontal well and the top of the target horizon according to the depth and the thickness of the target horizon.
4. An electrically heated coal seam underground gasification system as claimed in claim 3 wherein said horizontal well is in the form of a multilateral well;
the data processing apparatus is specifically configured to:
the spacing of the branches, the length of each branch well, and the well spacing per branch well are determined.
5. The electrically heated coal seam underground gasification system of claim 3, wherein the data processing device is specifically configured to:
determining the number of fracturing sections and the section distance of each section according to the length of each horizontal well;
the fracturing device is specifically used for:
and performing staged fracturing operation on each horizontal well according to the number of fracturing sections and the section distance of each section, and injecting a propping agent to keep the fracture in an open state after fracturing is completed.
6. The electrically heated coal seam underground gasification system of claim 1, wherein the electrical heating device is an electrical heater, a packer, and an injection line;
an electric heating device and a monitoring device are placed in the heating well, and lifting equipment and the monitoring device are placed in the production well;
the monitoring device comprises temperature detection equipment, pressure detection equipment, gas concentration detection equipment and gas yield detection equipment.
7. An electrically heated coal seam underground gasification system as claimed in claim 6 wherein the deepest heater well, the upper row of production wells are operated by:
the heater heats the heating well at the deepest position according to a first preset heating temperature and first preset heating power;
injecting water into the heating well at the deepest position by an injection pipeline according to first preset water injection data, wherein the first preset water injection data comprise water injection speed and water injection quantity;
when pressure detection equipment in the heating well detects that the formation pressure reaches a first preset formation pressure, stopping injecting water;
performing supplementary quantitative water injection through an injection pipeline according to the pressure detected by the pressure detection equipment in real time, and keeping the pressure coefficient within a first preset pressure coefficient range;
in a shaft above the packer, the pressure is maintained by supplementing a water column through an injection pipeline, so that the failure of the packer is prevented;
when the pressure detection equipment and the gas concentration detection equipment in the production well in the previous row detect that the casing pressure in the production well reaches a first preset casing pressure and the gas concentration reaches a first preset gas concentration, the lifting equipment in the production well starts to work;
when the temperature detection equipment in the production wells in the previous row detects that the temperature of the production wells rises to a first preset temperature, the heating temperature of the heaters in the heating wells is reduced to a second preset heating temperature;
when the daily gas production of the production well detected by the gas production detection equipment in the production well in the previous row is lower than a first preset daily gas production, the lifting equipment in the production well stops working;
the following operations are repeated for horizontal wells between the deepest and shallowest, which in turn are heating wells and production wells:
heating a row of horizontal wells serving as heating wells by a heater according to a second preset heating temperature and second preset heating power, stopping heating when heating for a first preset number of days, injecting gas into the heating wells according to first preset gas injection data through injection pipelines, and starting to work by lifting equipment in the row of horizontal wells above the row of heating wells when pressure detection equipment and gas concentration detection equipment detect that the casing pressure in the heating wells reaches a second preset casing pressure and the gas concentration reaches a second preset gas concentration; the second preset heating temperature is greater than the first preset heating temperature, and the second preset heating power is greater than the first preset heating power;
and when the temperature detection equipment and the gas concentration detection equipment in the horizontal well above the row of heating wells detect that the temperature in the horizontal well reaches a second preset temperature and the gas concentration reaches a third preset gas concentration, the lifting equipment in the horizontal well stops working.
8. An underground gasification method of an electrically heated coal bed, which is characterized by comprising the following steps:
the data processing device screens a target layer position meeting preset conditions, determines the distribution condition of the horizontal well according to the depth and the thickness of the target layer position, and determines the fracturing operation condition of the horizontal well and the injection heating and production operation condition of the horizontal well according to the distribution condition of the horizontal well;
the drilling device drills a plurality of rows of horizontal wells at a target layer according to the direction perpendicular to the maximum main stress direction based on the distribution condition of the horizontal wells; according to the depth of a target horizon, horizontal wells positioned between the deepest position and the shallowest position are sequentially used as a heating well and a production well;
the fracturing device performs staged fracturing operation on multiple rows of horizontal wells according to the fracturing operation condition of the horizontal wells, and injects a propping agent to keep fractures in an open state after fracturing is completed;
the electric heating device and the production device respectively perform different injection operations and heating operations on the multiple rows of heating wells and perform different production operations on the multiple rows of production wells according to the injection heating and production operation conditions of the horizontal well, and the temperature data, the pressure data and the gas production data in the injection operation and heating operation processes monitored by the monitoring device.
9. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the method of claim 8 when executing the computer program.
10. A computer-readable storage medium storing a computer program for executing the method of claim 8.
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